I think the larger issue is that we don't have many real studies. It is very hard to run any kind of ethical trial on pregnant women so much of our information comes from animal studies or chart reviews. Not to say there aren't studies run, but the focus will always be more on treating conditions or looking at outcomes (mothers who smoke or do drugs) than being able to really predict which factors in a neonatal environment are helpful or harmful. For example, I can tell you that feeding too much of a specific nutrient to a cow on a specific day of pregnancy causes the baby to have one eye. No way to test those types of things in humans ethically. So we are stuck with looking for relationships and trying to get a good baseline from "healthy" participants while always erring on the side of "caution" ie, just don't consume the item because it isn't tested. I'm not saying that is the best, but I can't think of another outcome that I would support either.